The invention relates to a pull-out guide assembly for .[.drawers.]. .Iadd.a drawer and .Iaddend.comprising a pull-out rail .Iadd.to be .Iaddend.fastened to the drawer, a supporting rail .Iadd.to be .Iaddend.fastened to the body of .[.the piece.]. .Iadd.an article of .Iaddend.furniture and a center rail differentially running between .[.said.]. .Iadd.such .Iaddend.two rails on each side of the drawer, running carriages holding load-transmitting cylindrical bodies being arranged between .[.said.]. .Iadd.the .Iaddend.rails, and driving rollers running on the supporting .[.rails.]. .Iadd.rail .Iaddend.and on the pull-out .[.rails.]. .Iadd.rail and .Iaddend.mounted on the center .[.rails.]. .Iadd.rail.Iaddend..
A pull-out guide assembly of the afore-mentioned kind allows substantially full extraction of the drawer from the .[.body of the piece of.]. furniture .Iadd.body .Iaddend.and hence guarantees optimal access to the contents of the drawer.
An example of such a drawer is described in U.S. Pat. No. 3,901,564.[.. Steel.]..Iadd., wherein steel .Iaddend.balls which are held in cages are used as cylindrical bodies in the pull-out guide assembly .[.described in the cited Patent..]..Iadd.. .Iaddend.These steel balls require relatively complicated profiles the supporting rails and of the pull-out rails. Furthermore, no run-in means for the drawer is provided because of the rail profiles.
To be able to use simpler rail profiles in connection with the same loading capacity, ball bearings would have to be used instead of steel balls according to the known state of the art. Ball bearings cause, however, a considerable increase .[.of costs.]. .Iadd.in cost.Iaddend..